1. Field of the Invention
The invention herein relates to intradermal injection devices, sometimes referred to as tattooing devices.
2. Description of the Prior Art
There have been intradermal injection or surgical devices for many years. They are commonly used to create decorative tattoos on a person's skin or to form permanent eyelid liners to replace paint-on cosmetic eyelid liners. The devices inject ink, dye or other marking fluid (referred to hereafter collectively as "ink" for brevity) just under the skin surface, so that the ink is retained within the skin and the color of the ink and the design formed by the ink injection pattern is visible.
The devices normally comprise a skin-penetrating needle which has the capacity to retain some quantity of ink or dye, a mechanism to reciprocate the needle for repeated punctures of the skin to implant the ink under the skin in the desired pattern, and a pen-like housing for the device which the operator holds and uses to guide the device. There are also some sort of off-on switch and power source for the reciprocating drive mechanism. With some devices the operator repeatedly dips the needle into an ink pool to coat the needle, while other devices have built-in reservoirs for the ink from which the ink is fed continuous to the needle.
A number of different devices, particularly with different types of reciprocating needle drives, have been disclosed over the years, and many of them have become commercial products. Typical of well-known devices are those described in U.S. Pat. Nos. 2,840,076 (Robbins: 1976); 4,508,106 (Angres: 1985); 4,644,952 (Patipa et al.: 1987) and 4,798,582 (Sarath et al.: 1989).
All of these devices have one or more disadvantages, however. One of the most significant is their inability to be readily and easily cleaned after use. While cleaning has always been recognized as important, in the past it was not uncommon for some operators to perform relatively low-level cleaning between consecutive uses, with full and thorough cleaning performed only periodically, such as overnight. This was because thorough cleaning required complex and time-consuming disassembly, including removal and retention of small parts, and/or lengthy immersion of the device in cleaning solvents such as acetone or in ultrasonic cleaning devices. Alternatively, a practitioner would have a number of devices, and would use each one only once before disassembling it for a thorough cleaning. Commonly the used devices were collected during the day and then at the end of the day all were disassembled and subjected to overnight cleaning.
Past devices also were structured so that some parts could only be cleaned with difficulty, particularly the drive mechanism. In the prior art devices the drive mechanism was in a direct line with the needle, and the rapid reciprocation of the needle would cause ink, sweat and skin fluids to be drawn into the drive mechanism, from which they could be removed only with great difficulty. Autoclaving was not feasible, because of the thermal degradation of the electrical components of the drive mechanism and the fact that an autoclave sterilizes but does not clean objects, so the time-consuming and difficult disassembly and subsequent ultrasonic or solvent cleaning was normally required.
Contaminated ink pools and ink residue within the devices also posed cleaning problems. Because disassembly was difficult and often incomplete prior to cleaning, inks and ink residues could accumulate in cavities within the device and serve as sources of contamination and disease.
Transmittal of diseases from one patient to another has always been the most important concern about use of the intradermal injection devices. In the past various infections of the skin could be transmitted. Serious as these were, however, they were normally curable if treated promptly. More recently, however, the appearance of the AIDS virus and its tendency to be transmitted primarily through openings and lesions in the skin or other bodily surfaces have transformed the context in which intradermal injection devices are used. Now transmittal of the infectious AIDS virus will result not just in an illness or minor skin infection, but rather with the inevitable death of the infected person. No longer can devices of the prior art type, with their inability to be easily and thoroughly cleaned after even a single use, be tolerated.
In order to accomplish this, however, it will be necessary to make fundamental changes in the basic design of such devices, such that a unit can be readily disassembled, quickly and thoroughly cleaned, and readily reassembled. It is to this end that the present invention is directed.